Trommel separators are used in the recycling industry for separating and classifying particles of diverse sizes. Rotary trommel separators, and any other such machine that can potentially handle large, bulky objects, often deals with the problem of jamming and ultimately the overloading of the motor. Steps have been taken to overcome this dilemma as illustrated in the following patents:
U.S. Pat. No. 4,619,407 to Goldhammer discloses a method for operating a shredding machine, which works via at least one drive train on cutter blocks of the shredding machine and which can be switched over into reverse to run automatically upon an overloading of the shredding machine.
U.S. Pat. No. 4,619,409 to Harper et al. shows a system for disposing of large amounts of waste materials whereas means are provided to monitor the unit and to take quick action to clear an overload condition therein or, if necessary, to shut down the system before serious damage results.
U.S. Pat. No. 4,786,000 to Weil et al. discusses a crushing apparatus comprising a bottle breaking member including a plate, and a punch extending outwardly from that plate. A V-shaped wall supports the bottle. If the crushing apparatus becomes jammed, the operator pushes the clear button which causes the bottle breaking members to reciprocate at a relatively low frequency.
U.S. Pat. No. 4,919,345 to Burlington et al. illustrates a shredding machine having oppositely rotating cutter shafts driven by an electric motor through an epicyclic gear mechanism. One of the shafts is driven directly, and the other through further gearing. The casing is mounted for limited movement under high load, a switch being provided to detect such movement, to stop or reverse the motor.
U.S. Pat. No. 5,248,100 to Arakawa discloses a rotor shearing type crusher for crushing waste. Any foreign material impossible to be crushed is separately discharged.
U.S. Pat. No. 3,812,967 to Rudzinski shows comminuting and screening apparatus for use in a rectangular liquid flow channel which may carry sewage or other fluid having solids which must be comminuted or removed. The cutting edges of the bits are angled such that hard solids tend to be rejected or pushed out of contact with the cutters to minimize sudden shock on the cutters and possible jamming of the rotor.
U.S. Pat. No. 3,749,004 to Pagdin et al. shows an apparatus for crushing having pairs of opposing crushing rollers. On roller from each set of rollers is rotatably supported by a frame. The other roller from each set of rollers is rotatably supported by a member movable relative to the frame.
U.S. Pat. No. 3,827,351 to Rosenow illustrates an apparatus for flattening metal cans and crushing lass containers. One of the rollers is mounted on a spring-biased yoke member to prevent jamming of the apparatus by a foreign noncrushable object which may enter the apparatus.
U.S. Pat. No. 4,346,850 to Westergaard discloses a shredding machine using a torque cushioning assembly. When a torque overload is applied to the comminuting shafts, a reaction is produced which tends to rotate the transmission casing relative to the frame. This rotation is resiliently resisted by the springs to cushion the impact on the teeth.
U.S. Pat. No. 4,128,154 to Voegein shows a positive engagement clutch to provide accurate alignment of intermittently operating cylinders with respect to the angular position of the machine drive shaft.
U.S. Pat. No. 4,342,396 to Fagnant et al. discloses a rotary parts separator. Small parts are separated from a mixture with larger members through rotation of a conical rotor mounted co-axially in a baffle. A friction clutch is mounted on the motor shaft which affords specific overload protection.
The above prior art summaries are merely representative of portions of the inventions disclosed in each reference. In no instance should these summaries substitute for a thorough reading of each individual reference. All the above references are hereby incorporated by reference.
In the recycling industry, operating conditions are usually very dirty, abrasive and very hard on the recycling equipment. Not only must the motor be protected from overload, but the power/gear unit should be totally enclosed. Gearing for several of the aforementioned patents was constructed externally, which would thereby expose and adversely affect the gears, roller chains and other power transmission components to airborne contaminants like glass dust, dirt, or other abrasive matter.
Gearing that was constructed internally, such as in U.S. Pat. No. 4,342,396, allowed for an effective clutch system which, in general, prevented overloading of the motor, but did not allow for specific adjustment of torque thereof being applied to the drum, nor the control of the amount of slippage thereto.
Furthermore, most mounts in the aforementioned patents were either unmovable, whereas the axial and radial inaccuracies of the shaft or rotating drum caused by manufacturing tolerances, wear or design, would destroy the mount and frame in a very short time; or designed to monitor slight movements in order to immediately turn off the motor in case of jamming, etc., thus causing unnecessary delays and repairs.